Microbes are generating a vast pool of marine methane that is contributing to global warming, scientists have confirmed.
Scientists from Queen Mary, University of London, traced the source of methane in the tropical Pacific Ocean.
Sediment collected from the ocean floor, where there is very little oxygen, revealed how bugs are creating the largest region of marine methane on Earth.
Methane is a potent greenhouse gas with 30 times more heat-trapping power than carbon dioxide.
Atmospheric levels of methane have increased in the last few decades, partly because of human activity. Scientists are keen to understand natural processes of methane production and consumption to assess the role played by humans.
Scientists aboard the Royal Research Ship James Cook spent six weeks mapping the methane pool between Panama and Hawaii. Their findings are published in the 'International Society for Microbial Ecology' journal.
"It's the first time anyone has successfully retrieved sediment from this part of the ocean and directly measured methane production using specialised equipment on board the research ship," Dr Felicity Shelley said.
"It is important we understand how microbes produce and consume this powerful greenhouse gas, especially in the oceans, where we understand very little."